Electrical insulator having sheds arranged at an angle to its axis

ABSTRACT

The invention describes a shedded insulator for supporting electric conductors particularly the conductors of overhead transmission lines. Instead of making the sheds normal to the axis of the insulator the sheds are arranged at an angle to a plane normal to the axis of the insulator. The sheds may be of the same or different diameters.

United States Patent 1 111 3,786,175 Proctor 1 Jan. 15, 1974 [541 ELECTRICAL INSULATOR HAVING SHEDS ARRANGED AT AN ANGLE TO ITS AXIS Inventor: Frank Hanslow Proctor, Gloucester,

Foreign Application Priority Data Apr. 27, 1971 Great Britain 11701/71 Aug. 17, 1971 Great Britain 38553/71 US. Cl 174/211, 174/179, 174/212 Int. Cl. HOlb 17/50, HOlb 17/60 Field of Search 174/140 S, 176, 177,

References Cited UNITED STATES PATENTS Vose .L 174 179 x FOREIGN PATENTS OR APPLICATIONS 467,799 l0/1928 Germany 174/179 1,921,299 11/1970 Germany 174/179 358,968 10/1931 Great Britain... 174/212 436,397 10/1935 Great Britain 1. 174/212 900,864 7/1962 Great Britain -l74/178 1,209,582 10/1970 Great Britain 174/212 Primary ExaminerLaramie E Askin [57] ABSTRACT 4 Claims, 1 Drawing Figure This invention relates to shedded electric insulators for high voltages and is directed more particularly but not exclusively to rod type insulators for suspending the conductors of overhead power transmission lines. The insulators may form crossarms or parts of crossarms or other structural members for supporting overhead line conductors from a pole or tower and can themselves be used for directly supporting such conductors, i.e., without the use of the pin insulators or insulator strings nor mally used.

Other conductors that can be directly or indirectly supported by insulators are, for example, bus-bars and the overhead contact wires or railway electrification systems; the insulators may for example be used as steady arms in such systems..The insulators may also form insulated bushings or post insulators.

The invention is concerned with that form of insulator for directly or indirectly supporting electrical conductors which comprises an elongated insulating member, for-example a member of resin bonded fibrous material, having a number of sheds provided on its surface.

It is an object of the invention to provide an improved composite electric insulator of this construction and to provide a method of making it.

According to this invention there is provided a shedded electrical insulator comprising an elongated core made of insulating material anda plurality of annular sheds made of insulating material disposed about said elongated core, each of said annular sheds having smooth surfaces tapering slightly towards each other from their center to their periphery and lying on opposite sides of a plane passing through the shed in which lies said periphery, said sheds being generally parallel to each other and with their respective planes arranged at an angle to a plane normal to the axis of the insula tor. Alternatively, only some of the adjacent sheds are parallel to each other. v

The sheds may be of the same diameter as each other or of different diameters and may be all arranged at the same angle so that when they. are cast or moulded, the two halves of the mould can be withdrawn, whereby only one casting operation is necessary.

The core may be a rod or tube'made of resin bonded inorganic fibres, for example-glass fibres, and may be covered with a hardenable resin or other suitable insulating material, for example cyclo-aliphatic epoxide resin, p.t.f.e.,silicone rubber, ethylene propylene rubis possible to cast or mould them onto the core in a single operation.

The material of the sheds is a hardenable resin or other suitable insulating material for example cycloaliphatic epoxide resin, p.t.f.e., ethylene propylene rubber, butyl rubber, silicone rubber, or other suitable polymeric material. The sheds may be of the same or different diameters.

' The principal function of the sheds is to increase the surface leakage path along the surface of the insulators which is more resistant to tracking than is the surface of the resin bonded glass fibre rod.

Instead of making all the sheds parallel to each other, the sheds may be arranged in a series of groups along the length of the core. All the sheds in the same group are parallel to each other but the sheds in one group are arranged differently from the sheds of the next group. For example if there are four groups in the series, the sheds may be all at an angle of say 75 to the axis of the core but the groups are radially. oriented differently, i,e., each group is turned through 90 with reference to the adjacent group. In this way it is still possible to cast or mould the sheds in one operation by providing separate mould, halves for each group of sheds.

The construction of the insulator above described will reating its efficiency to a marked degree due to the fact the sheds are constantly washed by the rain.

We claim:

1. A shedded electric insulator having a longitudinal axis and comprising an elongated rigid core of uniform diameter made of insulating material and a single integral moulding applied directly on said core and comprising a plurality of annular sheds made of insulating material and each separated from the next by an integral portion of said moulding, each of said annular sheds having smooth upper and lower surfaces tapering slightly towards each other from root to periphery and lying on opposite sides of a plane passing through the shed in which lies said periphery, said sheds being generally parallel to each other and with their respective planes arranged at an angle to a plane normal to the axis of the insulator. I

2. A shedded insulator according to claim lwherein the sheds are made of a material selected from the group consisting of cycloaliphatic epoxide resin, p.t.f.e., ethylen propylene rubber, butyl rubber, and silicone rubber.

3. A shedded electric insulator having a longitudinal axis and comprising an elongated rigid core of uniform diameter made of insulating material and a single integral moulding applied directly on said core and comprising a plurality of annular sheds made of insulating material and each separated from the next by an integral portion which is an inclined section of a generally ber, butyl rubber, or other suitable elastomeric material.

One form of insulator made according to this invention is illustrated in the accompanying drawing which is an elevational view partly in secton of a portion of an insulator.

Referring to the drawing, a composite insulator comprises a core 1 and a plurality of sheds 2 cast as a unit onto the core, the sheds 2 being spaced apart by cylindrical portions 2a of the casting. The plane of each shed, i.e., the plane passing through largest diameter of each shed, is arranged at an angle of say 75 to the axis of the core 1. The sheds 2 taper slightly from the core to the periphery. Owing to the fact that the sheds are all inclined at the same angle in the same direction it cylindrical portion and having upper and lower ends the planes of which are paralled to each other and inclined to said longitudinal axis, each of said annular sheds having smooth upper and lower surfaces tapering slightly towards each other from root to periphery and lying on opposite sides of a plane passing through the shed in which lies said periphery, said sheds being generally parallel to each other and with their respective planes arranged at an angle to a plane normal to the axis of the insulator and parallel to said inclined sections and the planes through the endsthereof.

4. A shedded insulator according to claim 3 wherein the sheds are made of a material selected from the group consisting of cyclo-aliphatic epoxide resin, p.t.f.e., ehtylene propylene rubber, butyl rubber and silicone rubber. 

1. A shedded electric insulator having a longitudinal axis and comprising an elongated rigid core of uniform diameter made of insulating material and a single integral moulding applied directly on said core and comprising a plurality of annular sheds made of insulating material and each separated from the next by an integral portion of said moulding, each of said annular sheds having smooth upper and lower surfaces tapering slightly towards each other from root to periphery and lying on opposite sides of a plane passing through the shed in which lies said periphery, said sheds being generally parallel to each other and with their respective planes arranged at an angle to a plane normal to the axis of the insulator.
 2. A shedded insulator according to claim 1 wherein the sheds are made of a material selected from the group consisting of cycloaliphatic epoxide resin, p.t.f.e., ethylene propylene rubber, butyl rubber, and silicone rubber.
 3. A shedded electric insulator having a longitudinal axis and comprising an elongated rigid core of uniform diameter made of insulating material and a single integral moulding applied directly on said core and comprising a plurality of annular sheds made of insulating material and each separated from the next by an integral portion which is an inclined section of a generally cylindrical portion and having upper and lower ends the planes of which are paralled to each other and inclined to said longitudinal axis, each of said annular sheds having smooth upper and lower surfaces tapering slightly towards each other from root to periphery and lying on opposite sides of a plane passing through the shed in which lies said periphery, said sheds being generally parallel to each other and with their respective planes arranged at an angle to a plane normal to the axis of the insulator and parallel to said inclined sections and the planes through the ends thereof.
 4. A shedded insulator according to claim 3 wherein the sheds are made of a material selected from the group consisting of cyclo-aliphatic epoxide resin, p.t.f.e., ethylene propylene rubber, butyl rubber and silicone rubber. 